PT or not, the story is that Vader took a tumble into lava. I don’t see any reason to omit the eyebrow removal change just because it kinda references the PT.
How about because it just looks very silly? Like Duracell said, he looks like Humpty Dumpty.
Maybe it’s the head shape. I already suggested to Adywan to make the head less egg-shaped, and he said he will try to do something about it.